Heart disease and stroke are the principal causes of mortality and long-term disability in developed nations. The major underlying cause of cardiovascular diseases is atherosclerosis, which is widely recognized as an inflammatory disease initiated by endothelial cell injury or dysfunction. Human cytomegalovirus (HCMV), a widely disseminated human pathogen, has long been proposed as a risk factor for cardiovascular disease. The pathogenesis of atherosclerosis involves interactions between multiple cell types and typically occurs in large to medium-sized arteries in regions that are branched or curved, which are exposed to disturbed patterns of blood flow and low fluid shear stress. To date, the role of HCMV infection in atherosclerosis has only been explored in static conditions. Given the importance cell-cell interactions and the role of blood flow in atherogenesis, the major goal of this research plan is to uncover key mechanisms in HCMV induced atherosclerosis in a physiological context using a flow model system. We plan to explore the bi-directional interactions of HCMV and endothelial cells under conditions of high or low shear stress in uniform and turbulent flow. To do this we will culture endothelial cells in chambers that will allow for the regulated flow of media over cells simulating blood flow. The use of uniform and step-flow chambers will allow us to simulate different types of flow patterns and shear stresses that occur in different parts of the vasculature. Using these systems we plan to analyze the effects of HCMV infection in endothelial cells exposed to varying flow patterns and shear stress as it relates to viral progression and proatherosclerotic gene expression at the protein and RNA level. In addition, we plan to determine how HCMV infection of endothelial cells in the context of flow ultimately modulates the adhesion and transendothelial migration of peripheral blood leukocytes, which is the major initial step in the development of atherosclerotic lesions. As a whole, this research plan is intended to explore the interactions between HCMV, endothelial cells, and leukocytes in the physiological context of blood flow in order to elucidate the mechanisms of HCMV induced atherosclerosis. Given the prevalence of HCMV in the human population (60-80% of adults), the mortality associated with atherosclerosis, and its impact on healthcare costs, there is a great need to determine the role of HCMV infection in the progression of atherogenesis in the physiological conditions that occur in the human artery. The long-term goal of this research plan is to provide novel insights into viral pathogenesis of atherosclerosis leading to cost effective new strategies for prevention of endothelial cell damage associated with HCMV infection.